The best choice of fertilizer for maize ( Zea mays ) and climbing beans ( Phaseolus vulgaris ) rotation for rich, mean and poor farmers in South Kivu, D.R. Congo

Many studies on fertilization of both beans and maize have been done, but most of the farmers don’t implement the recommendations because they can not afford the fertilizers’ cost at the recommended rate. From February 2008 to June 2010, an experimental study was conducted to investigate the effect of NPK, manure and a mixture of NPK and manure, to the rates that rich, mean and poor farmers can afford. The rich farmers could afford the recommended rate, the mean farmers could afford the half and the poor ones could only afford the quarter. After the first season, the rate of fertilizer was updated according to the income gained from the previous season’s production by each farmer type. For the five seasons of the trial, NPK gave the best yield for both crops, followed by the mixture and then manure for rich and mean farmers, but for poor farmers all the fertilizers gave almost the same result. But in water excess condition manure gave more stability of the climbing beans production, while the NPK’s outcomes were very unstable and the mixture gave an intermediate result. Farmers who didn’t apply fertilizers had the lowest yield. The farmers’ income followed the same evolution as their yield but not their investment capacities. All the fertilizers increased the investment capacity so as after four seasons, even poor farmers could afford the recommended rate. The fastest increase was obtained by both the mixture and NPK, followed by the manure alone and the lowest increase was obtained by farmers who didn’t use any fertilizer. The results of this study recommend improving agricultural productivity by increasing the use of inorganic fertilizers.